Reaction of Zinc with dilute sulphuric acid - Lab Work

To carry out the Reaction of Zinc with dilute sulphuric acid and classify it as physical or chemical changes

Aim

To carry out the Reaction of Zinc with dilute sulphuric acid and classify it as physical or chemical changes

Theory
Physical
Change: These changes can be observed and take place without changing
the composition of substances. There are no changes in chemical nature
of substance. The changes which can be observed are like change in
colour, boiling point, melting point, hardness, density, fluidity,
rigidity etc. The interconversion of states of matter is also a physical
change.

Chemical change: In this change, chemical
reaction takes place and completely a new substance with different
properties is formed. There are changes in chemical properties and
composition of substance.
ex: 2Mg(s) + O2(g) → 2MgO(s)
Here, the chemical composition and properties of product MgO is totally different from its reactants Mg and O.

Step 1: A big hard glass test tube is taken and fixed with clamp stand..
Step 2: Few pieces of zinc is put in the test tube.
Step 3: Some dilute sulphuric acid is poured in it so that the zinc pieces get immersed in the acid. Step 4: Immediately a cork is fixed, having delivery tube with a fine jet, on the mouth of the test tube. Step 5: A burning matchstick is brought near the mouth of the fine jet.

Observation
1. After adding dil. H2SO4 in the tube a brisk reaction starts and gas bubbles come out.
2. On bringing the flame, the gas coming out of the jet burns instantaneously with a small explosion or pop up sound which shows the presence of hydrogen gas.

Inference
1. The gas produced in the reaction is hydrogen. Zinc reacts with dilute sulphuric acid to produce hydrogen gas (H2) and zinc sulphate.

Zn(s) + H2SO4(g) → ZnSO4(s) + H2
(Zinc) (dil. sulphuric acid) (Zinc Sulphate) (Hydrogen gas)
This is an example of displacement reaction of a non-metal by a metal.
2. Zinc is more reactive than hydrogen.

4.ZnSO4 is different in chemical composition and chemical properties than Zn and H2SO4 so it is a chemical change.

Precautions
1. Use the chemicals judiciously.
2. Do not inhale gases evolved directly.
3. Hydrogen gas instantaneously burns with mild explosion. Therefore, a fine jet tube should be used to see the burning of hydrogen.
4. Handle acids and alkalies carefully.